#mask{
    background-color:#000;
    opacity:0.5;
    filter: alpha(opacity=50);
    position:absolute;
    left:0;
    top:0;
    z-index:9998;
    display:none;
}
#login{
    position:fixed;
    width:400px;
    z-index:9999;
    background-color:#fff;
    border-radius:15px;
    box-shadow:0 3px 4px #eee;
    display:none;
}